There is a considerable demand in a better image quality of ink-jet. The low smearfastness, waterfastness, and the tendency to smudge seem to be the main drawbacks of ink-jet, and the teachings herein address these issues.
Several techniques has been used in the prior art to address these issues. One such technique is underprinting, which helps to stratify the colorant to the surface of the paper, reduce wicking, and improve color performance. Underprinting is defined as applying a fluid to the substrate prior the ink deposition. There are several patents addressing the technique of underprinting for better waterfastness and bleed control. The underlying idea in underprinting is to bind the dyes with oppositely charged species. For example, anionic dyes can be bound by a cationic polymer, and cationic dyes can be bound by an anionic polymer.
Overprinting with a clear fluid is also known. For example, it is known to overprint ink-jet inks with a clear fluid that comprises a fusible material and then fusing the printed image with a fuser in the ink-jet printer, much like the fuser of a laser printer. While this approach is certainly suitable for providing improved permanent images, it does require modification of an ink-jet printer.
A need remains for a method for improving smearfastness, waterfastness, and smudgefastness in ink-jet inks.